Possibly the poster was done from a description of an early version of the script, certainly the city (?) on the bottom right of the poster doesnt look like anything in the film, there are several of what looks like Robert Vaughn's ship featured, and the Malmori fighters dont look quite right. The movie poster on the inside of the Cult Classics DVD box is much much better and faithful with decent artwork of Peppard, Vaughn, Thomas, Danning, Caymen, Saxon and a couple of ships - this was always the cover on British vhs copies of the film in the 80s and 90s.